Manufacture of microspheroidal gel particles



Dec. 4, 1951 w. A. REX EI'AL MANUFACTURE OF MICROSPHEROIDAL GEL PARTICLES 2 SHEET'S SHEET 1 Filed Dec-.

t 4 -06 W |\mN r 7 A a a; I i fiw m m. H t T 7 a a Q 4 OwJ w m x mm W T. g .M. 1 a q Rex Karl a]. flelsml o fzve rztor's 5g P h gg Dec. 4, 1951 w. A..REX ETAL MANUFACTURE OF MICROSPHEROIDAL GEL PARTICLES 2 SHEETS-SHEET 2 Filed Dec. 29, 1948 NT R k wa -Liz; gave-{1W8 Patented Dec. 4, 1951 x MANUFACTURE OF MICROSPHEROIDAL GEL PARTICLES Walter A. Rex, Westfield, and Karl J. Nelson,

Cranford, N. J., as'signors to Standard Oil Development Company, a corporation of Delaware I Application December 29, 1948, Serial No. 68,028

8 Claims. (Cl. 252448) The present invention relates to an improved process and apparatus for the production offfinely divided microspheroidal gel particles which may be employed arvantageously for catalytic cracking, adsorption and other purposes. i V It has been proposed to produce inorganic gels as fine, microspherical or microspheroidal particles by dispersing fine droplets of the desired sol in an' immiscible setting medium and maintaining the sol droplets in dispersed condition in that medium until they have set to firm gel particles. Theresultant gel particles are smooth spheres or spheroids which are especially advantageous in numerous processes, particularly those involving the fluidized solids technique since the smooth rounded particles reduce erosiono'f the equipment to a minimum and minimize losses of catalyst or contact particles due to attrition. 'Moreover, the necessity of grinding the gel in order toobtain the desired particle size distribution in the catalystor contact particle mass is avoided since the size of the'spheroids is readily controlled in the manufacturing process. One particular method of preparing spherical or spheroidal gel particles is the emulsion technique wherein a hydrosol of the desired gel is emulsified as the disperse phase in a water-im miscible liquid, agitating the emulsion to prevent agglomeration or coalescence of the'liydrosol particles until they have set to a geland'then separating the gel particles from the waterimmiscible liquid. The size of the gel particles may be controlled with a considerable degree of accuracy by varying the degree of agitation of the emulsion and the concentration of emulsifying agent employed. The'p'articles formed are remarkably' uniform in size and are spherical or spheroidal in form. In order to prepare spherical or spheroidal gel particles in commercial quantities, it is practically necessary to produce them continuously. A truly continuous system for setting and'ammoniating the hydrogel microspheres would involve adding the sol to several agitated reactors in series and withdrawing the set,- ammoniated gel'from the last vessel. Such a system has been found to be unsatisfactory for microspherical catalyst preparation, at least for the type of agitators, dispersion oils, emulsifying agents and hydrosol concentrations presently contemplated because of plugging of equipment, poor sphere formation and the difliculties in control. It is the object of this invention to devise a method and apparatus which will permit the pr u ti oie 9 319311 sphe i al el particles continuously and in large quantities.

It is also the object of this invention to prepare silica-alumina cracking catalysts of high activity and stability in spherical or spheroidal form continuously and in large quantities.

These and other objects will appear more clearly fromthe following specification and claims.

In accordance with the present invention, overall continuous performance of the system is achieved, by utilizing several batch reactors operated on a fixed time cycle. Fully automatic operation of the system can be achieved byproviding a timer which makes and breaks electrical contacts whichcontrolmotor driven or air actuated valves used throughout the reactor piping, Because of the setting characteristics of the, hydrosol employed in the process, it is highly important that stagnant spots be avoided in all transfer lines carrying this material. The sol must be continuously mixed, impregnated and pumped to the reactors. When shifting flow of sol from one reactorto another, dead spots are avoided in the lines in accordance with the present invention by the use of a pipe loop arrangement containing an orifice near the inlet to each side of the loop across which a substantial pressure drop is taken whereby the flow is distributed evenly between the two lines so that a positive fiowwill always be maintained in each line no matter which vessel is being charged with hydrosol. I V t In order to decrease the set time of the hydrosol, it is desirable to heat the sol. This is accomplished in accordance with the presentinvention by injecting steam directly into the hydrosol immediately before charging it into the reactors thereby avoiding the use of indirect/heat exchangers which would be rapidlyfouled by setting of sol to gel on its surfaces. Direct steam injection also avoids a substantial temperature gradient in the reactor which would be encountered if theoil washeated sufficiently to give the desired final temperature of the emulsion. Separation of the dispersed gel particles from the oil or dispersing liquid may be readily efiected by. means of heated water, part or all of which can be used to flush out thereactor after settingand ammoniation of the gel have been completed. The present invention further provides for clarie. fication of the dispersing oil in order to maintain the system in balance. g e The invention will be further described in reference 'to the accompanying drawing which is a schematic flowplan for the reactor system. "'In Fig. 1 of the drawing. is a supply'line to the desired point for admixture with the acid to form the silica hydrosol. The sodium silicate and the acid solution are continuously and in,- timately mixed together in a suitable mixing nozzle [5 in such proportions as to form a silica hydrosol of the desired composition and of definite set time. The set time must-be long'enough so that setting will not occur prior to charging to the reactor but short enough to-give ap'ractical setting time after heating and charging it into the reactor. For example, if the charging time of the reactor in the cycle of operations is fifteen minutes, the sol should have a set time of at, least eighteen to twenty minutes. If the set time of the sol is-less than-the charging time for thereactor, there is ate'ndency for so] introduced in the late stages of the chargin operation to deposit upon the sol particles first charged to the reactor which had at least partially set to gel.

The hydrosol is discharged from the mixing nozzle l5 into a mixing tank "5 which is provided with suitable agitating means. Aluminum salt, solution is continuously supplied to mixing tank l6 from supply tank H and is thoroughly mixed with the silica hydrosol. A stream of the aluminum salt impregnated hydrosol is passed through line 11 and divided into two substreams before being passed into a loop arrangement which will be described below in greater detail and thence into a suitable reactor.

In accordance with the present invention,

overall continuous performance is achieved by utilizing a plurality of batch reactors which are operated ona'fixe'd timingcycle. In this system, it is preferred to provide a total of five operating reactors and one spare reactor. In the attached drawing, two reactors are omitted from theline to simplify thedrawing. The reactors shown are numbered '20, 2l, 24 and 25 in the drawing.

A type of reactor suitable for the present invention is shown in application Serial No. 577,- 826, filed February 14, 1945, by J. A. Pierce, C. N. Kimberlin, Jr.,"and K. J. 'Nelson, and now 'abandoned. In general, the reactor comprises a large casing provided with a centrally disposed draft tube and a motor driven agitator mounted either in the upper or lower end of the casing. It is desirable to provide each reactor with suitable spray nozzle means for washing down the interior of the reactor at the end of each cycle. These spray nozzles may be conveniently arranged-upon two annular manifolds and so arrangedas to direct sprays of water against the top of the casing as well as againstthe inner Wall of the casing and both walls of the draft tube. Since these reactors are operated batchwise and are, therefore, only partially filled with dispersing oil when the introduction of sol is started, it is'desirable to out several slots in the upper part of the draft tube in order to permit circulation to take place before the reactor is filled to the top of the draft tube. V V

A s ss 'zfi, h n. n Fi 2, is Previded for thedispersion rnediurnwhiehg canbe a watereimmiscible material such. as acid treated lube oil stock or the like or a partially water-miscible medium such as butanol or the like. The dispersion oil is supplied through line 21, heat exchanger 28 to line 29 from which there is a valve controlled feeder line 30 into each of the reactors. In order to simplify the drawing, inevar o s f e a sle line t onl one actor, reactor 20 will be numbered, but it will be understood that each of the reactors is provided with the same piping and valve arrangements. A bleed oil line 3| is taken off the dis- '-persion medium line 21 for supplying small quantities of oil through lines 32 and 33 to both sides of the control valve 34 in the sol feed inlet line 35 in order toprevent, the sol from setting up in the inlet line during the periods when sol is not flowing through the inlet line 35. It will be understood that the sol inlet line will be so positioned as to provide ready drainage into the reactors and thereby prevent or minimize any tendency for the sol to accumulate in the feed inletlines. 4

The main sol inlet line H as indicated above the loop, it: is possible to insure substantially equal l w roug both Si e of h 19 :w each of the reactors. In this way, it, is possible o a ntain a c nt n ous fl of tn sh he entire 91 nlet in d e s o ch e.- ac'tor being charged with sol. If this special flow controlled 9PWI Q91 HE d a .sin l 0 inlet line wer P ev ew .0 weu d Q' through the entire line only when the further,- most reactor 25 is being charged. Since the sol nor al s e in t m Of om a out 1. m nu 9 to abput minu es it ld b ssa ovide eine me n for Pu gin th n t line r 0 to Prevent h sett q so; to el n th s sections o the in t ne where w is o occurrin This w ul req i eaddion fa l s We l as i u r m terial losses.

In order to increase the rate and shorten the time of setting of hydros ol to hydrogel, it is necessary to heat the sol. It has been previously propcse dto heat the hydrosol either by indirect heat ei ear se n aqe setiem e c er b ea n he 0, .9 uch n x nt eti e s91 ea ed to the es red m era ure in th r actor by contact with the oil. The first of these methods is objectionable becauseof the tendency of the sol toset in the exchanger tubes, or in transfer lines following the exchanger because of its relatively short set timelat the higher temperature. The. Second method is unsatisfactory use, of the t mpera ur rad n bta ned durins n rqs uct nhe 9 to the a t r- The sphere forming and particle size control characteristics of both the soland the oil phase vary appreciably withieven small changesin tem-,- perature, thus the temperature gradient greatly reducescontrol over particle size and shape.

In accordan'cewith the present invention, the hydrosol is heated to the desired reactor temperature by injecting steam into the sol inlet line 35 a short distance above the reactor. "36 is the main steam line andS-I is a valve controlled separator 46 shown in Fig. 2.

feeder line for supplying. steamtothe trans-i fer line 35. This steam injection technique effectively overcomes thegobjections to the other methods of. heating in that the sol priorto admission into the dispersion oil is at the. high reactor temperature only, in the relatively short length of pipe leading from the injection point into the reactor and temperature gradients during the sol addition are also avoided. Compensation is made for the dilution efiect of the steam condensate by adjusting the acid and/or sodium silicate concentrations and volumes used, in forming the hy.- drosol in mixing nozzlel5. l

When the hydrosol in reactorlfl has set to hydrogel spheres, it. is necessary to precipitate hydrous alumina, from the, aluminum salt by the addition of a suitable alkali, preferably ammonia. Liquid. anhydrous ammonia is withdrawn from storage tank (not shown) through line 38, vaporized in heat exchanger 3 9, and passedthrough main line 40 and valve controlled feeder line H into reactor 20. Upon completion of the ammoniation step, it is necessary or at least desirable-to'vent off 'each reactor before discharging the dispersion of gel particles from the reactor. Accordingly, a valved ammonia vent line 42' is provided on each of the reactors. The vent lines may discharge directly to the atmosphere or, in the event that the quantity of ammonia vented would constitute a nuisance, the vent line 42 may be discharged separately or the several vent lines may be manifolded and dischargedthrough a water scrubber (not shown).

After ammoniation and venting of ammonia, the reactor is discharged by opening flush valve 43 at the bottom and air-vent valve 44 at the top of the reactor permitting the oil-gel slurry to discharge through line 45 into the oil-water Provisions are needed for'fiushing the reactors after each batch to prevent setting and build up of gel on the reactor surfaces. The flushing is accomplished immediately after discharging the oil-gel mixture from the reactor by introducing water, preferably heated to about 200 F. into the reactor through water main 60 and inlet line 6| to the manifold and spray nozzles arranged as described above to permit thorough flushing of the interior surfaces of the reactor. During the period when water is not being admitted to thereactors for flushing, the water is divertedto the oilwater separator 46 through valved line 62 in order to adjust the concentration of the gel slurry to' an operable range for pumping. Since the water utilized in flushing the reactor is discharged through lines 45 and 48 into the oil-water separator it may be seen that this water is also efiectively utilized in the operation of the oil-water separator. I

The oil-water separator 46 is essentially a ZDorrv thickener and comprises a large tank 41 of sufficlent capacity to receive the contents of several reactors plus water for slurrying the gel .particles, a centrally disposed inlet pipe 48 and an annular bafiie 49 for preventing the short circuiting of oil-gel slurry to the oil overflow 50. The oil separated from the water slurry of gel particles passes over the overflow 50 into the surge tank and thence back into the oil storage tank 26. A baffle 63 is preferably-provided in order to prevent the froth or scum which accumulates at the top of the separator irom passing over the overflow with the oil. A rotatable arm 52 is arranged in the separator 46 inorder to prevent the gel particles from 'accumulatingor agglomerating' at the bottom of the tank 41 as well as. to assist in disengaging entrained oil droplets.

The slurry of gel particles in water is removed from separator 46 through line 53, filtered, and

water washed on the filter 54 to a sulfate content below about 2.5% and less than 0.3% NazO. The washed gel particles are reslurried in water and aged in tank 55 which is provided with a suitable motor driven agitator 56. The aged slurry is refiltered and washed on filter 57 whereupon the gel particles are dried in suitable rotary drying equipment (not shown).

Finely divided suspensions of solids and water of a colloidal nature tend to accumulate in the dispersion oil which adversely afiect the sphere forming properties of the dispersion medium. It is necessary therefore to provide means for clarifying the oil- This can be accomplished by substantially continuously withdrawing a stream of oil from the storage tank 25 equal to about 0.5 to

5.0% of the circulating stream, passing it through line 64 to heater 65 where it is heated under mild- 1y superatmospheric pressure such as about 10 lbs/sq. in. to about 215 F. to 235 F. The heated oil is then discharged through a pressure reduc-- ing valve 66 into flash-drum 51 wherein the water is flashed ofl at essentially atmospheric pressure, the water vapor leaving the flash drum at 58, the dried oil then being passed through line 59 to a suitable filtering or other separating means 10 for removal of solid materials contained in the oil.

Heating and flashing in this manner avoids foamingin the treatment of the oil and serves to eliminate all of the entrained water and substantially improved the filtration rate of the oil. The clarified oil is then recycled to the oil storage tank 26 through line I l.

Undesirable secondary emulsion of water, alu-.. minum floc, and hydrogel in oil is formed in sep--' arator 45 and must be removed and treated to recover its oil content. An oil-in-water type of emulsion is formed and accumulates near the water-oil interface while a water-in-oil type of emulsion is also formed and accumulates on top of the oillayer. Several outlet lines I5 are provided for withdrawing these emulsions from separator 4'1. Periodically these emulsions are Withdrawn from separator 46 through outlet lines 15 for the production of silica-alumina composite gel catalyst particles in spherical or spheroidal form. It will be understood, however, that it is broadly capable of use in the production of inorganic oxide gel particles in general such as silica gel, alumina gel as well as composite gels such as silica-magnesia and silica-alumina-magnesia gels.

The dispersion medium can be a hydrocarbon oil such as an acid treated lubricating oil stock, kerosene or the like, or it can be a partially water-miscible organic liquid such as normal butanol and the like or certain halogenated compounds such as carbon tetrachloride, ethylene dichloride, acetylene tetrabromide or the like. The

size and shape of the gel particles depends to a serv ces certain-extent upon :the =viscosity .-:of the a'dispers ixrg mediumandsaccordingly mixtures of materials to provide a dispersing medium of the-viscosity characteristics necessary... are also .lcontemplated. Normally the medium shouldshave aviscosity of between 1 and 20 .centipoises.

.The sizeand shapeoflthe gel particles also'depend upon'the following factors;

a. Degree of agitation during dispersion :of. sol in dispersing liquid.

.b. Amount of emulsifying :or surface active agent .used to accomplish dispersion.

c. Ratio of dispersing medium toisol.

.d. Temperatureof emulsion.

we. Composition of sol.

ifIhe degree nf :agitation during dispersion, as indicated intapplication SerxNo. 577,826referred toiabove shouldibe at a propellerperipheral velocityof about 1200 to 1400 it. per minute.

The amount of emulsifier used varies with the particular agent used as Well as the particular dispersing medium and is best determined empirically vfor the dispersion medium, sol,= etc.

The ratio .of dispersing medium to sol in the system should-be at least one to one andis generally about 5 to 1 although ratios as high as about to 1 can be used.

As indicated above, the composition of the .sol should beadjusted' to compensate for the-dilution caused by the steam condensate. The optimum temperature for setting of the solcan be readily determined empirically and if the determined optimum temperature does not represent 'a desirable operating temperature, the 131-101" compositionof the solmay be alteredor adjusted in order to give the desired setting time and/ or temperature.

The followng examples will seve to illustrate the manner in which the present invention may be carried out.

The catalyst prepared will conform to the following chemical analysis:

Weight per cent on bone dry catalyst SiOz 79-80 A1203 -19-21 S04 0.75 max. NazO 0.15 max. MgO 0.10 max. F8203 0.05 max.

"The following particle size specification will bemet:

Particle size:

.0-20 'microns :3-% max.

20-"200microns 90% min. 100+ microns 7% max. -l49 microns 992% "min.

.36 G. P. M. ofal B. sodium silicatesolution are withdrawnifrom storage tank l2 cooled to about 100 F. in heat exchanger 14 and mixed with 15 G. P. M. ofa 26 Be. sulfuric acid solution in mixing nozzle i5 and the resultanthydrosol .is discharged into mixing tank ll. About .19 G. P. M. of a 34.5 B. aluminum sulfatesolution are withdrawn from tank Hand intimately mixed with the silica hydrosol in mixing tank 1-0 to form 'impregnated hydrosol.

'A'n acid treated lubricating .oil stock from a coastal crude oil containing from 0.06 to 0.6 cc. .Alkaterge-Oper gallon is 'pumped into a .reactor at a temperature of about 160 F. iAlka-terge-O is a surface active agent :sold by Commercial Solvents Co. and is believedto bera substituted oxazoline in the form v:of an. oil-.-

soluble dark :ibrown wiscous ialiquid. When 'a fireactorzis .-.'about1-80% t 'filled withoil, r011 supply is dis continued, :and vigorous agitation Limp arited toithe oil. Impregnatedihydrosol'isthenisupplie'd to .the soliinlet line 35 at' the rate fo'f about 69 gals. per:minute while steam at 100 -.p. :s. i. g. ':-is supplied to the...inlet'line .35 through line 31 in sufiicientramount .t'o -raise :thetemperature o'f the hydrosol to about 161 F. At this temperature the: set time of the: impregnated ihydrosolis about 18 .minutes and accordingly agitation of the charged reactor .for :18 :minutes will suffice to convert the dispersed hyidros'ol droplets into spherical hydrogel p'articl'es.

.After setting is complete, ammonia, withdrawn fromrstoragesdrum.thru line 38,' vaporized :in heat exchanger 39 isintroduced into the reactcrin an amount sufficient to effect about neutralization .of the acid-- and to precipitate I the aluminum sulfate throughoutthe gelstructureas When this degree of ammoniation has been ef-- fected,;exc'ess:-ammoniais vented from the reactor and'the-reactorcontents aredumped into the oil separator :tank 46 whereupon the reactor is flushed with water at 200 F. to remove particlespf'zgelathat may :adhere to the reactor surfaces. The dispersion :oil separates fromlthe water :slurry of :gel particles and is :discharged from theseparator tank 46 throughov-erflow 50 and surge tank 5| into the oil'stora'ge tank 2 6.

:In order to. clarifythe dispersionoil and maintain its dispersing properties, oil is withdrawn from-storage tank :26 at the rate of 8.5 gals. .per minute, heated to 220 I. 'under a pressure of about 10 lbs. per square inch and then flashed dowmtoatmosp'heric ,pressure'toremove entrained water whereupon the .oil .is filtered to remove solids whereupon the clarified oil is returned-to the storage 2001* is passed-directly :to the :oil. feed 1 line :21

The water slurry of gel particles iswithdrawn through :line @5-3 and is filtered and washed on filter54 .to assulfate'content of'about 0.75%. The

washed-gel particles are then reslurried in water and then aged invtank 55 in-contact :with water atiabout200 :F. for aperiod of "at least 20 hoursafter; which 'theislurry of gel particles in water isiagainlfilteredzand washed-on filter 51 whereupon theggel dried. .This sequence of lfiltering andwashing prior toagingallows the salts to be easily removedandit substantially decreases the aging Ltime whichis absolutely essential for obtaming-catalyst"having superior catalytic -.qualities.

.fllhe importance of this sequence to catalyst purity and activity can be readily seen from :the following comparisons.

.In procedure 1, the water slurryof gel removed from the oil-water separator was washed and aged-concurrently. Aging was .for 48 hours at 200 F. whereupon the washed-and aged gel was filtered, idried and subjected to standard cracking tests.

lniprocedure 2, the water slurry of :gelrremovedfrom the coil-water separator was :aged .for 20 hours at 200 then washed, filtered and dried. The :resultant :{gel was subjected to the same standard cracking tests. 7

. -In :procedure..3, the water.slurry of'gellremoved from the-oil-water. separator, filteredand washed immediately, thenaged :fcr :20 ihours :at 200 filteredrwashedzandidried whereupon thezgel was The results obtained are summarized in the following table. Table I Procedure 1 2 s 3 S04 Wt. Per cent 2.3 0.8 0.8 N510, Wt. Per cent 0.51 0.22 0.05 Heat Stability, Per cent D+L on Heating at 1600 F. for three hours 31 33. 5 45. 6 Steam Stability, Per cent D+L on Steaming under 60 p. s. i. g. at 1050 F. for 24 hours 22. 9 24. 0 31. 8

Procedure 2 above was repeated except that the aging was for a period of 40 hours. The resultant gel particles contained 3.9% $04 and 0.67% of Na'zO.

Procedure 3 above was repeated except that the aging time was varied. The results are. summarized in the following table:

Table II Procedure 3 Aging Time, Hours 10 40 804, wt. per cent 0. 05 O. 5 0. 3 N810, wt; per cent 0. 09 0. O8 0. 11 Heat Stability, per cent D+L on heating 10. 3 45. 6 33. 8 atlflOO F. for three hours. Steam Stability, per cent D+L on heating is. 8 31. 8 31. 8

' under 60 p. s. i. g. at 1050" F.for 24hours.

It may be seen from the foregoing data that the sequence of washing out salts immediately followed by aging rather than by aging during washing or aging and then washing gives a more stable and uniform catalyst.

By employing a cycle timing device and suitable mechanically actuated valves it is possible to have the reactor system operate automatically. A typical cycle of operations for a single reactor Using a battery of five reactors as shown it would be possible to so integrate the cycle of each reactor that pumping of oil and sol would be continuous and at a uniform rate while the flow of ammonia would be periodic. The flow of water would also be continuous and uniform since it would be discharged directly into the oil-water separator 46 through line 62 when not needed for flushing down the reactors.

The apparatus of the present invention is described and claimed in copending divisional application, Serial No. 176,978, filed on August 1, 1950.

It will be understood that numerous variations are possible without departing from the scope of the following claims.

' What is claimed and desired to be secured by Letters Patent is:

. 1. A process for the production of an inorganic oxide gel in the form of microspheroidal particles by dispersion and gelation of a hydrosol of said oxide in an organic liquid setting medium which is at most only partially miscible with water, which comprises continuously withdrawing a l0 stream of the hydrosol from a common hydrosol source, dividing the withdrawn stream of hydrosol into two substreams forming a closed supply circuit having outlets to a plurality of separate 5 gelation zones, which zones are partially filled with the organic liquid setting medium and are distributed around the aforesaid circuit, and successively supplying the hydrosol from the circuit to each of the said gelation zones, whereby a continuous flowof hydrosol in all parts of the circuit is maintained at all times so that stagnation and gelation of the hydrosol in the circuit isprevented. 7 V

2. A process according to claim 1 wherein each of the substreams is passed through a flow restrictive zone which provides a pressure drop substantially greater than that which is incurred by either substream in its flow from the restrictive zone to any of'the said gelation zones.

3. A process according to claim 2 wherein the liquid setting medium is a hydrocarbon oil.

4. A process according to claim 2 wherein the liquidsetting medium is a hydrocarbon oil and wherein the hydrosol contains a silica hydrosol prepared by mixing analkali metal silicate with an inorganic acid, which process comprises the specific steps of heating the hydrocarbon oil setting medium to the optimum temperature for set ting the silica hydrosol, and heating the silica hydrosol at least to the temperature of the setting medium by injecting steam directly into the hydrosol just before the latter is discharged into the setting medium. v Y

5. A process for the production of inorganic oxide gels in the form of microspheroidal particles by dispersion of a hydrosol of said oxides in an organic liquid setting medium which is at most only partially miscible with water and which is recycled in the process, which process comprises dispersing hydrosol droplets in said organic liquid, agitating the mixture in order to maintain the hydrosol droplets dispersedas sepa rate discrete particles until the hydrosol has set to hydrogel, treating the resultant dispersion of hydrogel particles with water, separating a water slurry of gel particles irom the organic liquid, heating at least a portion of the organic liquid under superatmospheric pressure to a temperature above about 215? F., reducing'thepressure upon the heated organic liquid to substantially atmospheric pressure thereby flashing off any water entrained in the organic liquid, filtering the organic liquid in order to remove solid contaminants therefrom and reusing the clarified organic liquid for dispersing further quantities of hydrosol.

6. A process for the production of spheroidal silica-alumina cracking catalyst particles of uniform shape and size and high activity and stability which comprises continuously mixing sodium silicate and a mineral acid in suitable amounts to form a silica hydrosol, continuously adding an aluminum salt solution to said silica hydrosol, directly injecting steam into a stream of the aluminum salt-containing silica hydrosol to raise the temperature of the stream to at least the optimum temperature for setting the hydrosol to hydrogel, adding the heated stream 7 of hydrosol to a gelation zone partially filled with an organic liquid which is at most only partially miscible with water and which contains a surface active agent, the temperature of the organic liquid being substantially the optimum temper- 75 ature for setting the hydrosol, vigorously agitat 1-1 ing; the contents oftheegelati'onr zone during, the hydrosol additiontoemulsify the hydrosol, in the organic. liquid, converting the hydrosol to hydrogel, adding ammonia to.-thereactor in an amount sufficient to. -neutralize about 85% of the acid and precipitate'the aluminum: salt as aluminum hydrate throughout. the. hydrogeh. releasing ammonia-contained in-the gas-'phasezin the reactor, discharging the reactor contents and heated water into an organic liquid-water separator, withdrawing a stream-of organic liquid from the separator: and returning it to a: storage vessel preparatory to recycling it to the reactor vessel, withdrawing a water slurry of gelparticles from the-separator separately from said; oil stream, filtering andwashing the-water slurry of: gel particles, reslurrying' the. gel particles inwater at about 200 maintainingzthegelparticles in contactwith water at-or above that temperature for at-.-least 20 hours, filtering andiaga-in-washing the gel'par-ticlesand then drying-.the-latter.

'7. A- procession the continuous production. of

spheroidal silica-alumina particlesofhigh acttiv-ityand stability and .uniform sizewhichcomprises continuously; mixing. -a-.- sodium silicate so- .lution v and a sulfuric acid' solution. in a first mixing zone in amounts suitable to*form a=silica hydrosol; continuously withdrawing the resultant hydrosol and mixing and impregnatingit in a secondmixing. zone with analuminum sulfate solution. withdrawing a/stream of impregnated hydrosol from saidsecond mixing zoneand dividing said stream into two sub-streamswhich. form aclosedcircuit-having a plurality of outlets each leading .toone of a plurality of' gelation zonesdistributed around. the circuit, passing each of the two sub-streams through arestricted zonesw-hich provides a pressure drop: substantially greater than the pressurerdrops incurred by either substream. in its 'flow through. the circuit between therestricted-zone andany of the gelation zones, whereby a-continuous: flow of hydrosol in allparts ofv thecircuitis: maintained atalltimesand gelationofthe hydrosol-in. the circuit is'prevented; consecutively tapping ofi feed-istreams-of. impregnatedhydrosol and passing eachsuch-ieed stream through one oil aplurality of withdrawal zones spacedon said circuit downstream from said restrictedvzones, injecting-steam into' the. hydrosol streamin the withdrawalv zone. and promptly thereafter feeding. the. steameheated hydrosol stream. into oneof a-=plurality of gelation zones containing a pool-of hydrocarbonoil. maintained at substantially the optimum setting temperature of the hydrosol, dispersing. the. hydrosol in the oil pool and agitating the mixture until the dispersed hydrosol is converted into hydrogel partioles',- introducing ammonia,-v into the gelation zone to.precipitatealuminathroughout the gel structure, dumping the. resulting gel-in-oil dispersioninto a separation zone, washing out gel remaining in the gelation zone with hot water, mixing the resulting gel-containing wash. water withthe gel -in-oil dispersion, separating the oil from the resulting, water slurry of gel particles, withdrawing said water, slurry of particles from the separationzone, separating the gel particles from the slurry, washing and reslurrying the separated' particles in water, aging the reslurriedgel particles, separating the particles from the aged slurry and finally washing and drying the separated gelparticles.

8 2' In a process for" the" continuous production ofi' unif-ormspheroidal silica-alumina cracking catalyst particles of high activity and stability by: dispersion in oil-whichis recycled inthe process,, the improvement. which comprises continuously mixing a sodium. silicate solution having'a density of about 25B. and cooled to about 100 F. withza sulfuric acid solution having a density of about 26 B. in a first mixing zone, the volumeratio of silicate solution to sulfuric acid so.- lution being about.2.4/1, continuously discharging the resultant hydrosol to. a second mixing zone and there mixing the said hydrosol with an aluminum sulfate solution having a density of about.34.5 Be. to form an impregnatedihydrosol, thevolume ratio ffhydrosol to aluminum sulfate solution. being abouti51/ 19; Withdrawing astream ofimpregnated hydrosol from said'second'mixing zone and dividing said stream into, two substreams which forma closed circuit havinga plurality of outlets each leading, to. one of a plurality of gelation zones distributed around the circuit, passing each of thetwo sub-streams through a restricted zone which provides a pressure drop of about to lbs./sq; inch'which is substantially greater than the pressure drop i'ncurred'by either sub-stream in its flow in the circuit between the restricted zone and any ofthe gelation zones, whereby a continuous flow ofhydrosol in allparts of the circuitis maintained at all times and gelation of the hydrosol in the circuit isprevented, consecutively tapping oirfeed. streams of impregnatedhydrosol and passing each such feed stream through one of a plurality of withdrawal zones spaced on said circuitdownstream' from said restrictedzones so as to maintain continuous flow in all pa-rt'sof said circuit, bleeding oil through the withdrawal zones'not actually used for'withdrawing hydrosol was to prevent residual hydrosolfrom setting up in the unused withdrawal zones, injecting steam at about 100 p. s-.' i. g. into the hydrosol feed stream being withdrawn, the injected steam being in sufficient amount'to-raise the-temperature of the feed stream to about 160 Ft, promptly charging said heated feed' stream to oneof a plurality of gelation zones containing an agitated poolof hydrocarbon oilhaving a vis- 4; cositybetween l and- 20 centipoises, heated to about 160 F. and admixed with a small amount of a surface activeagent; the charging being continued until the 'ratioof sol to oil in the gelation zone-isbetween-about 1:5 and 1:1, but in any case the time used for charging the hydrosol to the-reaction zonebeingshorter than the setting time of. the. hydrosol; directly thereafter shutting oii the: aforesaid feed"v stream and starting to tap another feedstream from the sub-stream circuit totone; of the. other gelation zones for forming another batchiof catalyst particles; dispersing the hydrosol in the aforesaid oil pool and continuing the agitation of the mixture for about 15 to 60 minutes to convert thev dispersed hydrosol drop- 60 lets into spherical hydrogel particles; thereafter introducing ammcniagasinto said gelation zone in amount sufficient; to efiectaibout;85% neutralization of the acid. present. and to precipitate the alumina throughout the gel structure, venting ex- 65 oess ammonia, dumping the. resulting gel-in-oil dispersion into; a separation. zone, thoroughly flushing residual gel from the emptied gelation zone with" water at about 200 F. and discharging the resulting mixture of gel and water also into 70 said. separation zone; separating the. oil from the resulting water. slurry'cf; gel particles. and. passing; the separated oil to an: oilstorage. zone for sub.- sequent recyclingto one ofthe gelation zones to form an oil pool therein, withdrawing a minor 75 streamer. oil from the bottom portion. of said oil Iii storage zone and heating said minor oil stream circulating in presthe process to flashing said minor oil sure of about 10 p. s. i. g.,

stream down to atmospheric pressure to vaporize 5 entrained water therefrom, filtering solids from the dewatered oil and returning the resulting clarified oil to the process; withdrawing the water slurry of gel particles from the aforesaid separation zone, filtering said slurry, washing the filtered gel particles to a sulfate content of about 0.75%, reslurrying the filtered, and washed gel particles in water, aging the resulting reconstituted water slurry at about 200 F. for at least 20 hours, filtering the aged slurry, and finally washing and drying the filtered gel particles for use as catalyst.

WALTER A. REX.

KARL J. NELSON.

14 REFERENCES crrs'n The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 2,384,946 Marisic Sept. 18, 1945 2,412,958 Bates et a1 Dec. 24, 1946 2,418,232 Marisic Apr. 1, 1947 2,429,751 Gohr et a1. Oct. 28, 1947 2,435,379 Archbald. Feb. 3, 1948 2,442,387 Valas June 1, 1948 2,464,329 Marisic et a1 Mar. 15, 1949 2,467,470 Gerhold et a1. Apr. 19, 1949 

1. A PROCESS FOR THE PRODUCTION OF AN INORGANIC OXIDE GEL IN THE FORM OF MICROSPHEROIDAL PARTICLES BY DISPERSION AND GELATION OF A HYDROSOL OF SAID OXIDE IN AN ORGANIC LIQUID SETTING MEDIUM WHICH IS AT MOST ONLY PARTIALLY MISCIBLE WITH WATER, WHICH COMPRISES CONTINUOUSLY WITHDRAWING A STREAM OF THE HYDROSOL FROM A COMMON HYDROSOL SOURCE, DIVIDING THE WITHDRAWN STREAM OF HYDROSOL INTO TWO SUBSTREAMS FORMING A CLOSED SUPPLY CIRCUIT HAVING OUTLETS TO A PLURALITY OF SEPARATE GELATION ZONES, WHICH ZONES ARE PARTIALLY FILLED WITH THE ORGANIC LIQUID SETTING MEDIUM AND ARE DISTRIBUTED AROUND THE AFORESAID CIRCUIT, AND SUCCESSIVELY SUPPLYING THE HYDROSOL FROM THE CIRCUIT TO EACH OF THE SAID GELATION ZONES, WHEREBY A CONTINUOUS FLOW OF HYDROSOL IN ALL PARTS OF THE CIRCUIT IS MAINTAINING AT ALL TIMES SO THAT STAGNATION AND GELATION OF THE HYDROSOL IN THE CIRCUIT IS PREVENTED. 